[rendall]

> This idea that "life support" is the most difficult aspect is unfounded.

It's an unknown. While we have manned rockets, we have never entirely isolated a group of humans from the biosphere for even a year, never mind indefinitely. The times it was tried, it failed. As the article points out, it is not an experiment that can be done piecemeal. All elements must be in place and interacting before the effects are known: lack of gravity, radiation shielding, recyclers, scrubbers, years of time, etc

[mcculley]

> we have never entirely isolated a group of humans from the biosphere for even a year

Lunar Palace 1 made it to 370 days: https://en.wikipedia.org/wiki/Yuegong-1

[elurg]

A lot of stuff is known about it. Both the US and USSR first operated long-duration space stations nearly half a century ago.

Gravity and radiation are well understood and we can definitely build machinery that can tolerate them well for many years.

> we have never entirely isolated a group of humans from the biosphere for even a year, never mind indefinitely. The times it was tried, it failed.

Why doesn't the ISS count? It gets resupplied every few months but a Mars base would be resupplied every two years so systems only have to scale to last 10x as long.